WASHINGTON — A federal appeals court on Tuesday upheld a finding by the Environmental Protection Agency that heat-trapping gases from industry and vehicles endanger public health, dealing a decisive blow to companies and states that had sued to block agency rules.

The judges unanimously dismissed arguments from industry that the science of global warming was not well supported and that the agency had based its judgment on unreliable studies. “This is how science works,” they wrote. “The E.P.A. is not required to reprove the existence of the atom every time it approaches a scientific question.”

In addition to upholding the E.P.A.’s so-called endangerment finding, the court let stand related rules setting limits on greenhouse gas emissions from cars and limiting emissions from stationary sources. Opponents had also challenged the agency’s timetable for enforcement and its rules singling out big polluters, but the court said the plaintiffs lacked the standing to do so.

Fourteen states, led by Virginia and Texas, had sued to block the rules. Fifteen states, including New York, California and Massachusetts, went to court to support the agency. Massachusetts and California were among the states that won a landmark Supreme Court decision in 2007, Massachusetts v. Environmental Protection Agency, that led to the agency’s endangerment finding. The attorney general of Virginia said he would appeal Tuesday’s ruling.

In 2009 and 2010, Congress debated whether to legislate limits on carbon dioxide emissions, with backers arguing that imposing agency rules instead would be clumsy and expensive. The House passed a bill, but the legislative effort died in the Senate.

“This decision ensures that a regulatory approach to emissions cuts will take place, whether or not Congress acts legislatively,” said Paul Bledsoe, a senior adviser at the Bipartisan Policy Center, a nonprofit group that specializes in energy and environmental issues. “The question is, does the industry push Congress to develop a more efficient, less costly approach now that regulation is inevitable?”

But Representative Fred Upton, the Michigan Republican who is chairman of the House Energy and Commerce Committee, said that Congress’s refusal to approve greenhouse gas limits constituted a decision and that lawmakers should act now to reverse the E.P.A. emissions rules. Carbon regulation “threatens to drive energy prices higher, destroy jobs and hamstring our economic recovery,” he said.

Industry is divided on regulating climate-changing gases, with the oil, gas, coal and most of the electricity sectors opposing emissions limits and automakers supporting them. In a statement, the Alliance of Automobile Manufacturers noted that car companies had made huge investments to improve fuel economy and thus reduce carbon dioxide emissions and that a unified emissions standard was among its “top national priorities.”

Environmental groups cheered the decision. “This is a slam-dunk victory for E.P.A. and for the Clean Air Act,” said Frank O’Donnell, the president of the group Clean Air Watch.

Joseph Mendelson III, a lawyer with the National Wildlife Federation who was involved in persuading Massachusetts to file a suit demanding that the E.P.A. regulate greenhouse gases, noted how long the battle over climate-altering gases had dragged on.

The decision “puts to rest the big polluters’ attempts to deny the E.P.A.’s ability to limit carbon pollution,” he said. But, five years after the pivotal Supreme Court decision, legal squabbles are still “delaying the obvious and prevent us from getting to the question of how do we best do it,” he said.

The panel’s opinion was unsigned. The chief judge, David B. Sentelle, was appointed by President Ronald Reagan; he was joined by two Clinton appointees, David S. Tatel and Judith W. Rogers.

The politics of carbon dioxide regulation have grown more partisan over the years. When Massachusetts first brought the case that led to the landmark Supreme Court decision, its governor was Mitt Romney. As the presumptive Republican nominee for president, he has since backed away from his earlier position that human-caused global warming is under way.

According to his Web site, one of his policy goals now is to amend the Clean Air Act, the critical law under which the E.P.A. is now acting, “to exclude carbon dioxide from its purview.”

A version of this article appears in print on June 27, 2012, on page A13 of the New York edition with the headline: Court Backs E.P.A. Over Emissions Limits Intended to Reduce Global Warming. Order Reprints|Today's Paper|Subscribe